Al Lopez Park in Tampa is normally an oasis of serenity on a Monday. But on the last day of open enrollment for health insurance under the Affordable Care Act, the community center was crowded, noisy and stressful. Hundreds of procrastinators came seeking help from navigators.

It was a microcosm of the nation, as 3 million Americans visited the HealthCare.gov website and another 1 million used the call-center line on the last official day to sign up for a 2014 health plan.

Under a barrage of last-minute shoppers, the website suffered technical problems for six hours early in the day, sprang back to life and then faltered again from noon to about 1:30 p.m. Floridians and residents of 25 other states use the federal website to shop for insurance.

Those who could not file applications on the website were sent to a “virtual waiting room,” and could leave contact information to enroll later in the week. Phone messages were also accepted at the call center.

Anyone who made a good-faith effort to enroll will be allowed to sign up after Monday’s deadline, the White House said last week. Officials have not clarified exactly how many days of leeway are being granted.

At the Tampa park’s community center, navigators were working with the uninsured in the computer room and on laptops in other rooms, even outside at picnic tables. TV cameras were everywhere.

A woman with orange hair who declined to talk to reporters kept a list of names and called them whenever a navigator was free.

One of those in line was Karen Lindquist, 56, who lost her child-care job and health insurance seven years ago. Now she babysits, and pulls money from her 401(k) to make ends meet. She was pushing a stroller with a 1-year-old named Noah.

“I’m a little disappointed that I’m being forced to buy something I probably can’t afford, so we’ll have to wait and see what they offer me,” she said.

But when the wait stretched to two hours, she had to leave to pick up other children after school. It was the third time she had tried to get help signing up at a community center, she said, but each time she left, thwarted.

Contacted by phone later in the day, Lindquist said she was online at Healthcare.gov, trying to figure it out for herself.

Another uninsured person in line was Michael Hill, 48, who works a couple of part-time jobs. His main job is at Home Depot, one of the corporations that decided to drop its coverage for part-timers – a limited-benefit plan that didn’t meet the law’s standards -- on Jan. 1.

Hill had been irked because he had thought that under the federal health law known as Obamacare he’d be able to keep his health plan. But his opinion of the law rose after a navigator helped him enroll in a silver Humana plan.

“It actually turned out to be cheaper than what I had before,” Hill said. With tax credits, he’ll pay $55 a month.

His friend Amisha, who was reluctant to divulge her age and last name, said she doesn’t have health insurance even though she has a job in an office-supply store. She wasn’t able to complete enrollment in a plan on Monday because HealthCare.gov went on the fritz just as she and the navigator began, but she was told she’ll be able to finish later in the week.

Another of those in line was Maite Casanova, 52, who said she is a dentist but has been unemployed and uninsured for five years, ever since her divorce. She and her ex-husband, also a dentist, used to practice together.

She’s trying to open her own practice, she said, but in the meantime, she needs a health plan.

Her income was too low to qualify for a subsidy at HealthCare.gov, she discovered. She is one of the low-income people who fall in a gap, who would have qualified for Medicaid if the Florida Legislature had accepted federal funds to expand it.

Dr. Casanova will get health care another way: she lives in Hillsborough County, which has a sliding-scale health plan financed by a half-penny sales tax. So she will not have to go without a physical exam much longer.

Her brother lives in Switzerland and she marvels at how everyone there has health insurance automatically, without the hassles or expense that Americans face. “I think everybody should have health care, regardless,” she said.

Another who shares that view is Walt Seely, 71, a volunteer for the non-profit group Get Covered, America who was manning the door at the community center. Since he is insured by Medicare, he doesn’t need to sign up for a plan, but he encourages others to.

Seely was a school principal for the U.S. military forces and lived in Europe for 23 years, mostly in Germany. Civilian medical facilities there were good, he said, and fees much lower than here -- especially for drugs. Europeans don't worry about going bankrupt from medical bills, he said.

Seely would have preferred to see the U.S. move in a similar direction, expanding Medicare to all ages.

“Leaving it in the hands of profit-making companies is not the way we ought to be doing it,” he said. “But it was a step, it was something rather than nothing, which is what we had before.”

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HealthCare.gov was to be taken down for maintenance after midnight, coming back into action Tuesday morning with a new home page and explanation for consumers on how to use their new coverage. There will be a portal for enrollment for those who have “special circumstances” that require them to get new coverage, such as losing a job, getting divorced, etc.

The health law requires that almost all Americans carry health insurance or pay a penalty at tax time in 2015. Close to 1 million Floridians will be exempt from the requirement, like Dr. Casanova, because their income is below the poverty line – about $11,500 for an individual. The Affordable Care Act would have covered them through an expansion of Medicaid, and the federal government provided the funds to do so, but the Florida House declined it.

The penalty for refusing to obtain insurance is $95 per adult or slightly less than 1 percent of income, whichever is greater. Most people will be in the latter category; an individual whose income is $35,000 would owe $249. The exact calculation is complicated; see this explanation at Kaiser Health News. The penalty rises significantly in 2015.

If you're uninsured, now's the time to buy a plan. Monday’s the end of the annual open enrollment period when people who don’t have coverage through their employers can sign up on or off their state’s marketplace. With limited exceptions, people who miss this enrollment window will be unable to sign up for health insurance until next fall for coverage that starts in January 2015.

In addition to being uninsured, you will face a penalty for not having coverage. The fine may be bigger than you expect. Here are the details: